@MissMaria,
First: Yes you tell him. You don't have to call him. Text messages are fine, e-mail probably better. This is obviously a very difficult confession, and writing will help you choose your words more carefully. Further, it will give him the chance to read and re-read what you wrote. At first, he is going to have the inevitable shock and will probably try to speak to you immediately, you don't have to pick up, in fact, I suggest you don't for at least a few hours, and I'm sure he will be texting you or e-mailing back rather quickly.
Second: You say you are tired of the distance thing, and so that is why you cheated on him. Does that mean you want the relationship to end, or are you hoping your actions will motivate him to make a move to get closer to you?
Third: The fact that you were physically intimate with 2 different people, suggests that you have a certain pattern; what would it take for you to break this pattern? That is the key for earning his trust again if you truly love him, and not just think you do. In that case, you should realize the blame is on your own ability to control your sexual desires for which you can easily change and become more in control of your sexual choices.
Last: Regardless how you feel about him, the fact remains you are in a relationship with him. If you want to do what is right, you would tell him either way so that he can know the truth and analyze how he wants to proceed. You owe this to him by the unwritten laws of ethics, yet there are no enforcers to this law but you and yourself only. You may fear losing him, but do you really want someone who wouldn't stay with you had they been aware of the truth? Imagine your wedding day, wouldn't the back of your mind be thinking "if he knew..would we still be here..would he still feel this way about me?" If you want to live a lie the rest of your life, it is going to drag you down further and further the deeper and longer your relationship becomes with him.